Curious Brass Damage

[matrixcs]

Found these at our club. Does anyone know what might cause this damage to factory ammo?
The brass exhibits flow into some shape at the rim and in some the rim shows cracking.
The primer is dented to nearly it's full depth.
169970

[trails4u]

I'm guessing a headspace problem..... fired in wrong chamber???

[shredder]

From the look of the case heads, my guess is that these cases have seen some very high pressures. It appears that the brass has flowed into a recess in the breech face of whatever they were fired in. Cracked rim? Never seen that in normal brass. I would chuck em.

You may be on to something with your comment about perhaps being fired in the wrong chamber.

[matrixcs]

A little more info.. These were collected after s LEO session at the club. Not reloads but factory ammo. Firing pin hits are deeper than any others I have seen. Case dia. is within reasonable 9mm dim. so the chamber seems correct. I wonder if it is some auto with a serious bolt smash into the case?

[Virginia John]

I am thinking that their armorer has modified the firing pin. Do we know if this came from only 1 or all LEOs using the range at that time?

[matrixcs]

I am thinking that their armorer has modified the firing pin. Do we know if this came from only 1 or all LEOs using the range at that time?

Looks like just one shooter the vast majority of the brass looks fine maybe 50 rounds out of 800 or so..

[trails4u]

Modified pin might explain the deep strikes, but I don't think that explains the flow of brass at the caseheads. Are we sure they were factory? I'm just not sure what would do that other than pressure or headspace issues?????

[matrixcs]

Modified pin might explain the deep strikes, but I don't think that explains the flow of brass at the caseheads. Are we sure they were factory? I'm just not sure what would do that other than pressure or headspace issues?????

I'm 99.9% sure I collected all the brass and there were only the 2 headstamps on the range that day and only LEO which never use reloads... It is very curious ... I would never use brass this abused..

[M-Tecs]

Open bolt SMG maybe?

[ReloaderFred]

It looks to me like it was fired in a submachine gun that fires from the open bolt. They normally use a large fixed firing pin and the bolt slams pretty hard when it's released by the sear.

Hope this helps.

Fred

[shorty500M]

2nd that notion of an openbolt smg

[trails4u]

The LEOs have gone UZI..... Cool. :)

[OS OK]

Why don't they show gas cutting through the holes and carbon residue?

[koehlerrk]

The LEOs have gone UZI..... Cool. :)

Spray and pray LEOs... Sounds about right anymore.

[17nut]

It looks to me like it was fired in a submachine gun that fires from the open bolt. They normally use a large fixed firing pin and the bolt slams pretty hard when it's released by the sear.

Hope this helps.

Fred

Look at this poor 9mm iron case:
http://i295.photobucket.com/albums/mm153/Chickenthief/Skydning/Til%20andre/R0011329_zpse954e447.jpg (http://s295.photobucket.com/user/Chickenthief/media/Skydning/Til%20andre/R0011329_zpse954e447.jpg.html)
http://i295.photobucket.com/albums/mm153/Chickenthief/Skydning/Til%20andre/R0011331_zps522cad91.jpg (http://s295.photobucket.com/user/Chickenthief/media/Skydning/Til%20andre/R0011331_zps522cad91.jpg.html)
http://i295.photobucket.com/albums/mm153/Chickenthief/Skydning/Til%20andre/R0011328_zpsfa4a9736.jpg (http://s295.photobucket.com/user/Chickenthief/media/Skydning/Til%20andre/R0011328_zpsfa4a9736.jpg.html)

[GONRA]

GONRA sez listen to M-Tecs and successors posts....

[Scharfschuetze]

M-Tec probably nailed it. On the other hand, I've shot numerous models of open bolt SMGs and I don't recall seeing such brass flow on the heads. I see two NATO marked cases in the photo and they also display the same firing fingerprint as the civilian ammo, so it certainly wasn't an ammo issue with the Federal cartridges. Simply gun related I guess.

I don't see any vertical striations on the cases, so we can rule out the most used SMG in US police service: the MP5. I agree that the primers look like they were struck by a fixed firing pin (often part of the bolt face) which is common on most of the open bolt SMGs.

Many of my 9mm and 45 ACP cases for reloading are from SMGs from both police and military ranges when I didn't have to turn the brass in. None of them ever displayed those bolt face marks. Interesting.